A. Field of the Invention
This invention relates to keratometers, and in particular, to an automated keratometer, including one that is relatively small in size, and hand-held.
B. Problems in the Art
1. Definition of Keratometer PA1 2. Manual Keratometers PA1 3. Automated Keratometers PA1 4. Size and Space Considerations PA1 5. Needs in the Art PA1 6. Objects
A keratometer is an instrument utilized to measure the radius of curvature of a curved surface; generally that of an eye. Readings are usually taken of the radius of curvature of two different axes, as well as the angle of those two different axes. The results are utilized to estimate the dioptric power along each axis, which can then be used to estimate refractive power and/or shape of the particular eye being tested.
The primary readings taken by the keratometer are the curvature along the axis of maximum curvature, the curvature along the axis of minimum curvature, and the angles of the two curvature axes with respect to the horizontal axis. These types of readings are used to fit eye glasses or contact lenses. Accuracy is therefore important. This is particularly true for contact lenses which are placed in direct contact with the surface of the eye.
Keratometers are also used to examine the pathology of the cornea for such things as keratoconus, dystrophies, and stigmatism, corneal problems, and abnormal curvature. It is usually a standard piece of equipment for an optometric or ophthalmic examination.
Keratometers originally were all manually operated optical devices. They continue to be used today. A manual keratometer requires the patient's head to be accurately positioned and maintained in position with respect to the device. Manual dials are then turned by the operator to create some optically perceivable condition in the device. Some manual keratometers require the operator to align several circles in a particular orientation while viewing the patient's eye. A reading is then taken from the dials or, in the earliest versions, a chart is consulted to obtain the readings. These readings must then be manually transcribed.
Manual keratometers represent a substantial investment, and require substantial space in an office for the patient and operator to complete the procedure. Perhaps the most significant problems of manual keratometers are the amount of time required to take the appropriate readings and the amount of training and expertise needed by the operator to achieve reliable results.
Operation of these devices requires some level of advanced skills and knowledge. They generally must be operated by ophthalmologists, optometrists, or perhaps opticians. Some judgment and experience on a rather high level is needed to take and interpret the readings and create the conditions needed to ensure the readings will be generally accurate and reliable.
Manual operation includes potential for human error. The operator must take significant care in the procedures and may need to retake the measurements to double check original measurements. Sometimes interpretation of results is needed, requiring substantial expertise.
Manual keratometers generally allow apical measurements only, and do not allow peripheral Cornea measurements. New surgeries and treatment techniques require accurate peripheral measurements. Manual keratometers also have a number of moving parts and rely on expensive high precision optical elements. Calibration and the maintenance of calibration is therefore very important. All of the above discussed problems leave room for improvement in this field.
In an attempt to meet these needs, automated keratometers have been developed. These devices generally utilize some electro-optical combination to provide keratometric readings which can be displayed, stored, or sometimes printed. Major deficiencies of present automated systems are as follows.
Many of these devices require a substantial amount of manual operation. Some require that the operator align the instrument to the eye by viewing and aligning images in the keratometer optical system. One requires alignment of lights and geometric figures. This requires the operator to subjectively determine whether a certain somewhat subjective condition exists, introducing an element of error risk.
These systems require the user's head to be fixed with respect to the machine. Normally this will include a chin or head brace and necessitates constant vigilance to ensure that the head is kept in a fixed position.
Most automated keratometers take up a substantial amount of space. Many consume the better part of a medium sized table. The operator sits on one side of the machine, while the patient sits on the other. It might also require associated equipment, taking even more room.
It is to be understood that the size of some automatic keratometers is so large that it must be put in a separate room, or at least a room outside of the normal examination room. This requires additional patient shuffling from the waiting area to the examination room, to the room for the keratometric readings, and so on. This further complicates and is an obstacle to efficiency of patient processing. It can create a bottle neck if all the patients need to go to a separate room, have keratometric readings taken, and then return to the examination room.
Auxiliary equipment such as motorized tables and chairs is sometimes utilized with the automated keratometer to accurately position the patient. This adds significantly to the cost and to the space needed for operation. These machines tend to be heavy and their inner contents somewhat fragile. Most also require precise optical components. They are also extremely costly as compared with manual keratometers.
Automated keratometers therefore include potential errors associated with the requirement of human verification or subjective determinations. They also rely on precise, costly optical components which must be maintained in precise alignment and calibration.
They also require a high level of operator training and expertise. The added cost and space required for these devices may therefore offset any improvement they provide in time or accuracy.
Keratometers are generally utilized in the offices of ophthalmologists and optometrists. They may also be utilized by opticians. Keratometric measurements are often taken for each patient's visit. This is especially true for those who wear contacts. The keratometer measures the curvature of the eye. The contact, to be fitted properly, is placed directly adjacent to the eye. Most ophthalmologists and optometrists set up "lanes" in each examination room. Patients are called from the waiting room and moved through a series of equipments or stations in the lane during eye examinations.
Much consideration is given into maximation of patient flow or turnover. Several patient rooms with completely furnished lanes are therefore utilized. While one patient is put through the measurements in the lanes, another patient can be brought into another room and prepared. A third patient who has finished with measurements can then be readied for completion of the exam while the ophthalmologist or optometrist goes to another room and/or another patient.
Time and space are primary factors in improving the efficiency of patient flow. More time to perform the keratometric measurements, translates into less time available to do other things. More room for the keratometer, translates into less room for other equipment, or a reduced number of patient rooms; which translates into more square footage and more costly office space. Less costly and smaller manual keratometers, are more time consuming to operate. Automated keratometers, take up much more room and are more cumbersome.
With current keratometers it is not possible to delegate the taking of keratometric readings to staff members. They require either substantial training and/or substantial expertise, knowledge, and skill to operate. These traits may not be readily available in staff members. At a minimum, there is a requirement of extensive or long training and experience. Otherwise accuracy and reliability may suffer substantially.
While automated keratometers are generally much more costly than manual keratometers, the trend is to purchase and use automated keratometers. There is a perception, perhaps primarily by patients, that automated, higher technology equipment is a necessity for competent and successful ophthalmological and optometric practice.
Although automated keratometers are available, their problems and deficiencies are readily apparent as discussed above. A need therefore exists for an automated keratometer which is small in size, takes all keratometric readings quickly, accurately and reliably, and is easy for staff workers or technicians to operate.
There is also a need for a portable automated keratometer that need not be placed on a table nor require constraint of the patient's head. There is also a need for an automated keratometer which is less costly than current automated keratometers.
It is therefore a principal object of the present invention to provide an automated keratometer which solves the problems or improves over the deficiencies in the art.
Another object of the present invention is to provide an automated keratometer which is substantially automatic and eliminates substantially the margin of human error in its operation.
A still further object of the present invention is to provide an automated keratometer which can be hand held, is easily maneuverable, light weight, and can even be battery powered.
A still further object of the present invention is to provide an automated keratometer which does not require fixed positioning of the patient's head or eye with respect to the device.
Another object of the present invention is to provide an automated keratometer which has an automated alignment system to ensure alignment during measurement.
Another object of the present invention is to provide an automated keratometer which helps patients fix on a target to eliminate possible measurement errors caused of loss of fixation or movement of the eye.
Another object of the present invention is to provide an automated keratometer which automatically processes, displays, and stores or prints keratometric readings.
Another object of the present invention is to provide an automated keratometer which allows the user to simultaneously view the patient's eye.
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.